Methods of making paper tissue, towel, and the like, are well known, including various features such as Yankee drying, throughdrying, fabric creping, dry creping, wet creping, and so forth. Conventional wet pressing processes have certain advantages over conventional through-air drying (TAD) processes including: (1) lower energy costs associated with the mechanical removal of water rather than transpiration drying with hot air, and (2) higher production speeds, which are more readily achieved with processes that utilize wet pressing to form a web. On the other hand, through-air drying processing has been widely adopted from new capital investment, particularly, for the production of soft, bulky, premium quality tissue and towel products.
Fabric creping has been employed in connection with papermaking processes that include mechanical or compactive dewatering of the paper web as a means to influence product properties. See U.S. Pat. Nos. 4,689,119 and 4,551,199 to Weldon; U.S. Pat. Nos. 4,849,054 and 4,834,838 to Klowak; and U.S. Pat. No. 6,287,426 to Edwards et al. Operation of fabric creping processes has been hampered by the difficulty of effectively transferring a web of high or intermediate consistency to a dryer. Note also U.S. Pat. No. 6,350,349 to Hermans et al., which discloses wet transfer of a web from a rotating transfer surface to a fabric. Further United States Patents relating to fabric creping more generally include the following: U.S. Pat. Nos. 4,834,838; 4,482,429 and 4,445,638, as well as U.S. Pat. No. 4,440,597 to Wells et al.
In connection with papermaking processes, fabric molding has also been employed as a means to provide texture and bulk. In this respect, there is seen in U.S. Pat. No. 6,610,173 to Lindsey et al. a method of imprinting a paper web during a wet pressing event which results in asymmetrical protrusions corresponding to the deflection conduits of a deflection member. The '173 patent reports that a differential velocity transfer during a pressing event serves to improve the molding and imprinting of a web with a deflection member. The tissue webs produced are reported as having particular sets of physical and geometrical properties, such as a pattern densified network and a repeating pattern of protrusions having asymmetrical structures. With respect to wet-molding of a web using textured fabrics, see, also, the following United States Patents: U.S. Pat. Nos. 6,017,417 and 5,672,248 both to Wendt et al.; U.S. Pat. Nos. 5,508,818 and 5,510,002 to Hermans et al. and U.S. Pat. No. 4,637,859 to Trokhan. With respect to the use of fabrics used to impart texture to a mostly dry sheet, see U.S. Pat. No. 6,585,855 to Drew et al., as well as United States Patent Application Publication No. 2003/0000664, now U.S. Pat. No. 6,607,638.
Throughdried, creped products are disclosed in the following patents: U.S. Pat. No. 3,994,771 to Morgan, Jr. et al.; U.S. Pat. No. 4,102,737 to Morton; and U.S. Pat. No. 4,529,480 to Trokhan. The processes described in these patents comprise, very generally, forming a web on a foraminous support, thermally pre-drying the web, applying the web to a Yankee dryer with a nip defined, in part, by an impression fabric, and creping the product from the Yankee dryer. A relatively permeable web is typically required, making it difficult to employ recycle furnish at levels which may be desired. Transfer to the Yankee typically takes place at web consistencies of from about 60% to about 70%. See also, U.S. Pat. No. 6,187,137 to Druecke et al. As to the application of a vacuum while the web is in a fabric, the following are noted: U.S. Pat. No. 5,411,636 to Hermans et al.; U.S. Pat. No. 5,492,598 to Hermans et al.; U.S. Pat. No. 5,505,818 to Hermans et al.; U.S. Pat. No. 5,510,001 to Hermans et al.; and U.S. Pat. No. 5,510,002 to Hermans et al.
As noted in the above, throughdried products tend to exhibit enhanced bulk and softness. Thermal dewatering with hot air, however, tends to be energy intensive. Wet-press operations wherein the webs are mechanically dewatered are preferable from an energy perspective and are more readily applied to furnishes containing recycle fiber, which tends to form webs with less permeability than virgin fiber. Many improvements relate to increasing the bulk and absorbency of compactively dewatered products, which are typically dewatered, in part, with a papermaking felt.